Create shared styles for icon stroke

[joshblack]

We need to author shared styles similar to how we do now for IDL and our tokens but specifically targeting icon stroke. This issue is for creating the command and code necessary for generating these shared styles.

The naming convention for this feature is: color / border / <color> / <grade>

We have a couple of options when it comes to commands, but we could add it to existing color sync commands or do a standalone command. Either works!

[laurenmrice]

here is a sketch file with an example of how the color styles should be:
https://ibm.box.com/s/uz7nrdlt1o9szlzb6rz96kti1q8u4fnp

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Trying to decide which naming convention makes more sense from a code and sketch perspective. border or stroke. From a sketch perspective, border makes more sense, is this the terminology you are using in code?

[emyarod]

in code it's a stroke but I named it border in my draft PR and will probably keep that since that's what it's called in Sketch

[laurenmrice]

ok cool lets go with border